WASHINGTON (Reuters) - President Barack Obama on Friday said Russia's troop buildup on the Ukraine border was out of the ordinary and called on Moscow to pull its military back and begin talks to defuse tensions.

"You've seen a range of troops massing along that border under the guise of military exercises," he said on CBS "This Morning" in Vatican City. "But these are not what Russia would normally be doing."

Obama said the moves might be no more than an effort to intimidate Ukraine, but could be a precursor to other actions.

Obama made his comments at the end of a visit to Europe, where the United States, Germany, France, Britain, Italy, Japan, and Canada warned Russia it faced additional damaging sanctions if it takes further action to destabilize Ukraine.

Governments in Washington and Europe are in discussions about possible measures against Russia's energy sector but have signaled they would hold off on more sanctions unless Moscow goes beyond the seizure of Crimea.

Obama in his interview with CBS lamented that Putin seemed stuck in a Cold War mentality.

"You would have thought that after a couple of decades that there'd be an awareness on the part of any Russian leader that the path forward is not to revert back to the kinds of practices that you know, were so prevalent during the Cold War," he said.